JPH0141363B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting a reflux liquid in a distillation apparatus, and more particularly to a method for adjusting a reflux liquid for increasing the amount of middle distillate when distilling multi-component hydrocarbons.

Conventionally, for example, crude oil was converted into gasoline, kerosene, light oil,
When distilling and fractionating heavy gas oil and heavy oil components, the first
This is carried out based on the flow sheet diagram of the crude oil atmospheric distillation apparatus shown in the figure.

To briefly describe the distillation fractionation system using this device, crude oil supplied from a crude oil supply pipe 1 is sequentially preheated in each heat exchanger 2 to 6, and then introduced into a heating furnace 7, where gasoline, kerosene, light oil, etc. The heavy gas oil component is vaporized and becomes the heavy oil component (hereinafter referred to as normal pressure residual oil).
is heated to a temperature at which it becomes liquid and introduced into the atmospheric distillation column 8. In this atmospheric distillation tower 8, the vaporized components move upward, and during this movement, they are distilled and fractionated in the order of their boiling points, that is, heavy gas oil, gas oil, kerosene, and gasoline, starting from a predetermined position. Light oil collection pipe 9, light oil collection pipe 10, kerosene collection pipe 11
and is discharged from the gasoline sampling pipe 12. Incidentally, only gasoline is discharged as a gas from the top of the atmospheric distillation tower 8, and is discharged from the gasoline sampling pipe 12 via a gas-liquid separator 13.

On the other hand, while the liquid-liquid atmospheric residual oil is led to the bottom of the atmospheric distillation tower 8, the light components contained therein are vaporized and separated (stripped) by the steam from the steam pipe 14, and then the atmospheric residual oil is The oil is discharged from the oil sampling pipe 15. Each component extracted from the atmospheric distillation column 8 is sent to a tank (not shown) or sent to the next purification step. Note that 16 is a gasoline reflux liquid pipe.

In this crude oil atmospheric distillation equipment, since the content of each component varies depending on the type of crude oil, the operating conditions of the atmospheric distillation equipment are determined according to the type of crude oil, and each component is separated according to the content ratio. However, it is not always theoretically perfect; for example, light oil with a boiling point close to heavy diesel oil is mixed with heavy diesel oil, and conversely, heavy diesel oil has a boiling point close to that of diesel oil. The substance is mixed with light oil. The same applies to other components.

Incidentally, in recent years, the demand for kerosene and light oil among the various components of crude oil has increased, and it is desired to increase production by distilling and fractionating these as completely as possible.

Therefore, conventionally, when increasing the production of light oil, for example, the valve 17 of the light oil sampling pipe 10 of the atmospheric distillation tower 8 is opened wider than usual to increase the amount of light oil extracted. As the amount of extracted gas increases, the internal reflux liquid to the heavy gas oil distillation section in the atmospheric distillation tower 8 decreases, so that from a certain point on, the heavy gas oil becomes more heavily mixed into the gas oil. For this reason, a method has been used to increase the temperature at the outlet of the heating furnace 7 into which the crude oil is introduced, thereby increasing the heat supply into the distillation tower 8 and increasing the internal reflux liquid. Not only is this not advantageous from a thermoeconomic standpoint, but there is also the problem of increased decomposition of petroleum products due to high-temperature heating.

The present invention was made in view of the above circumstances, and
A portion of the component to be increased in production collected in the atmospheric distillation tower is heated to above the boiling point of this component using the heat source of the distillation equipment, and then introduced into the atmospheric distillation tower again. By extracting the reflux liquid from the atmospheric distillation tower section, dissipating the heat, and then reintroducing it into the atmospheric distillation tower, the reflux liquid in the distillation section of the component to be increased can be increased, thereby increasing the production of the target component without any problems. The purpose is to

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a flow sheet diagram of a crude oil atmospheric distillation apparatus to which the first embodiment of the present invention is applied. In FIG. 2, crude oil is supplied from a crude oil supply pipe 21 to a gasoline vapor extraction pipe 29 and a kerosene collection pipe 3, which will be described later.
5. After being sequentially preheated by the heat exchangers 22 to 26 installed in the light oil collection pipe 36, heavy gas oil collection pipe 37, and atmospheric residual oil collection pipe 47, the oil is introduced into the heating furnace 27. Here, the crude oil is heated to a temperature at which the gasoline, kerosene, light oil, and heavy light oil components are vaporized and the heavy oil component (atmospheric residual oil) is in a liquid state, and then introduced into the atmospheric distillation tower 28. Ru. In the atmospheric distillation column 28, the atmospheric residual oil is led to the bottom, while the vaporized components move upwards.During this movement, they are cooled by the reflux liquid and are divided into descending order of boiling point: heavy gas oil, gas oil, kerosene. Then, gasoline is distilled and fractionated. Among these, kerosene, light oil, and heavy light oil are extracted from each sampling pipe 35, 36, and 37 in a liquid state.
5, 36, and 37, it exchanges heat with the crude oil in the aforementioned heat exchangers 23, 24, and 25, is further cooled to an appropriate temperature in each cooler 38, 39, and 40, and is discharged. Only gasoline is extracted in a gaseous state from the top of the atmospheric distillation tower 28 through a gasoline vapor extraction pipe 29, exchanges heat with crude oil in an interposed heat exchanger 22, and is further cooled in a cooler 30.
The gas is introduced into the gas-liquid separator 31. Here, the gas and gasoline fraction are separated, and the gasoline fraction is discharged from the gasoline collection pipe 34, but a part of this fraction, that is, the amount required for distillation fractionation, is distilled at atmospheric pressure via the gasoline reflux liquid pipe 33. It is refluxed to column 28 and the temperature at the top of the column is controlled. On the other hand, the gas is discharged from the gas vent pipe 32.

The process of collecting each component is the same as before, but
In the present invention, when increasing the production of a component to be produced, for example, light oil as in this embodiment, a light oil extraction pipe 41 is provided to extract a part of the light oil from the atmospheric distillation tower 28 to the outside of the tower 28, as shown in FIG. Provided, the extraction pipe 4
The light oil extracted through 1 is exchanged with the exhaust gas discharged from the heating furnace 27 through the gas discharge pipe 42 in the heat exchanger 43, heated to a temperature higher than its boiling point, and then subjected to normal pressure distillation approximately equal to this heating temperature. Reintroduced into column 28 section. The amount of light oil to be extracted is set so that the reflux ratio after increased production (the amount of reflux liquid in the light oil extraction stage relative to the amount of gas oil extracted) is the same as or greater than the reflux ratio before increased production. In addition to the above operation, a reflux liquid pipe 44 is provided above the gas oil collection pipe 36 of the atmospheric distillation tower 28 to draw out the reflux liquid, and the reflux liquid in the atmospheric distillation tower 28 is drawn out from the reflux liquid pipe 44. , a heat exchanger 45 installed in the crude oil supply pipe 21
After being cooled by heat exchange with crude oil, it is introduced into the atmospheric distillation column 28 again.

By these operations, the amount of reflux liquid in the gas oil fractional distillation section in the atmospheric distillation column 28 can be increased.
For this reason, the degree of refinement of light oil is improved and the production of light oil can be increased. Moreover, since the exhaust heat in the system is used, the energy saving effect is large.

On the other hand, when the atmospheric residual oil is guided to the bottom of the atmospheric distillation column 28, a small amount of light components contained therein are vaporized and separated by the steam from the steam pipe 46 when the atmospheric residual oil is guided to the bottom. (Stripping)
Thereafter, it is extracted from the atmospheric residual oil sampling pipe 47, cooled appropriately through the heat exchanger 26 and the cooler 48, and then discharged. Note that each discharged component is sent to a tank or to the next purification process. Next, a specific example of this embodiment will be explained using FIG. 3.

For example, 25,200 barrels of Arabian crude oil/
A specific example of processing per day (4006 KL/day) is shown in the figure.

Light oil content is 17.8% of crude oil, or 4490 barrels/
The internal reflux ratio of the light oil extraction stage at this time was 4.04.

In this example, we increased the amount of light oil and extracted a portion of it.
When 25.6 KL/hour was heat exchanged with furnace exhaust gas (398°C), it was heated to 273°C, so this was reintroduced to the upper part of the heavy gas oil extraction stage (292°C).

As a result, the amount of heat input is reduced below the light oil sampling stage.
It increased by 1,322,000 Kcal/hour, which increased the internal reflux ratio of the gas oil extraction stage (assuming the amount of gas oil extracted remains the same) to 5.06.

Therefore, even if the amount of light oil extracted is increased by 15% (4.5 KL/hour), the internal reflux ratio will only decrease to 4.4, compared to the conventional
Compared to 4.04, there was more margin at the end, so the degree of distillation of light oil was good.

On the other hand, the amount of internal reflux liquid above the light oil extraction stage also increases due to the increase in the amount of heat input, and the amount of heat this has is used to heat the crude oil by exchanging heat with it. In this example, 42 KL/H of internal reflux liquid was withdrawn at 243°C and, after heating the crude oil, was returned to the tower from below the kerosene extraction stage at 185°C.

As a result, the internal reflux liquid in the kerosene extraction stage was reduced to the same level as before.

FIG. 4 shows a second embodiment of the invention.

The difference between this embodiment and the first embodiment is that the heating source for light oil, which is extracted from the atmospheric distillation tower 28, heated, and then reintroduced into the distillation tower 28, is not the exhaust gas from the heating furnace 27, but is The purpose is to utilize the thermal energy possessed by the atmospheric residual oil extracted at high temperature from the bottom of the pressure distillation column 28.

That is, a light oil extraction pipe 51 is provided branching off from the light oil collection pipe 36, and the extraction pipe 51 is connected to a predetermined position of the atmospheric distillation column 28 via a heat exchanger 52 interposed in the atmospheric residual oil collection pipe 47. Connecting. In this configuration, a part of the gas oil to be collected is led to the heat exchanger 52 via the gas oil extraction pipe 51, where it exchanges heat with the atmospheric residual oil from the atmospheric distillation tower 28 and is heated to a temperature above the boiling point. After that, it is reintroduced into a portion of the atmospheric distillation column 28 whose temperature is approximately equal to this heating temperature. Note that the other operations are the same as those in the first embodiment, and the explanation will be omitted.
In this embodiment, as in the first embodiment, the amount of reflux liquid increases and the production of light oil can be increased without any problems, and the energy saving effect is large.

Further, FIG. 5 shows a third embodiment.

In this embodiment, the preheated crude oil is introduced into the flash tank 55 before being introduced into the heating furnace 27, where light gasoline is evaporated, and this light gasoline is directly introduced into a section of the atmospheric distillation column 28 whose temperature is approximately equal to this temperature. Introduced via piping 56, while flushing tank 55
The cut crude oil from which light gasoline has been separated is introduced into a heating furnace 27 from the lower part of the distillation tank, and after being heated, it is introduced into an atmospheric distillation column 28. Then, a part of the heavy gas oil is mixed with the crude oil before being introduced into the heating furnace 27 through the heavy gas oil extraction pipe 57 provided by branching from the heavy gas oil collection pipe 37, and heated together with the crude oil in the heating furnace 27. It is then reintroduced into the atmospheric distillation column 28.
The rest is the same as the other embodiments, and the explanation will be omitted. This case also has the same effect as each of the above embodiments.

In the first and second embodiments, light oil was described, but the same applies to kerosene, and in this case, the reflux liquid is drawn out of the distillation tower from a position above the kerosene sampling pipe. Further, in the third embodiment, only heavy gas oil is mixed into the crude oil, but kerosene, gas oil, heavy gas oil, or a mixture thereof may also be mixed. Furthermore, the present invention is not limited to crude oil,
It can also be applied to the distillation of similar multicomponent hydrocarbons, such as fluid catalytic cracked oil, heavy hydrotreated refined oil, and heavy hydrocracked oil.

As explained above, according to the present invention, a portion of the component to be produced, which is collected in the atmospheric distillation tower, is reheated using an already provided heat source or waste heat, and then reintroduced into the distillation tower. The reflux liquid is extracted from the distillation tower section above the sampling stage for this component and is reintroduced into the distillation tower after being radiated, resulting in a large energy-saving effect and the ability to increase the reflux liquid without any problems, increasing the production of the desired component. can do.

[Brief explanation of drawings]

FIG. 1 is a flow sheet diagram of a conventional crude oil atmospheric distillation apparatus, FIG. 2 is a flow sheet diagram of a crude oil atmospheric distillation apparatus to which an embodiment of the reflux liquid adjustment method according to the present invention is applied, and FIG. A flow sheet diagram showing a specific example of one embodiment, and FIGS. 4 and 5 are flow sheet diagrams of a crude oil atmospheric distillation apparatus to which different embodiments are applied, respectively. 21...crude oil supply pipe, 27...heating furnace, 28...
...Normal pressure distillation tower, 36...Light oil collection pipe, 41, 51
... Light oil extraction pipe, 42 ... Gas discharge pipe, 4
3, 45, 53... Heat exchanger, 44... Reflux liquid pipe, 47... Normal pressure residual oil collection pipe.

Claims (1)

[Scope of Claims] 1. An oil liquid containing a plurality of components with different boiling points is heated in a heating furnace and then introduced into an atmospheric distillation tower, and when the components vaporized by the heating ascend in the atmospheric distillation tower, they become reflux liquid. In a distillation apparatus in which each component is distilled and fractionated by contacting with the distillation column, and each component is collected from each sampling stage provided in the distillation column, a selected part of the components to be collected is After reheating the oil to a temperature equal to or higher than the boiling point of the component, the oil is reintroduced into the atmospheric distillation column section which is approximately equal to the heating temperature, and the reflux liquid is extracted from the atmospheric distillation column section above the selected component sampling stage. A method for adjusting a reflux liquid in a distillation apparatus, characterized in that the reflux liquid in the distillation section of the selected portion is increased by reintroducing the liquid into the atmospheric distillation column after being used as a source for preheating the liquid. 2. The method for adjusting reflux liquid in a distillation apparatus according to claim 1, wherein the selected component is reheated using heat of exhaust gas from a heating furnace that heats the oil liquid. 3. The method for adjusting a reflux liquid in a distillation apparatus according to claim 1, wherein the selected component is reheated using heat from atmospheric residual oil extracted from the bottom of the atmospheric distillation column. 4. The method for adjusting reflux liquid in a distillation apparatus according to claim 1, wherein the reheating of the selected component uses a heating furnace that heats an oil liquid.